GHSA-9R6P-6XQ4-MRQ9
Vulnerability from github – Published: 2026-04-13 15:31 – Updated: 2026-04-18 09:30In the Linux kernel, the following vulnerability has been resolved:
netfilter: x_tables: restrict xt_check_match/xt_check_target extensions for NFPROTO_ARP
Weiming Shi says:
xt_match and xt_target structs registered with NFPROTO_UNSPEC can be loaded by any protocol family through nft_compat. When such a match/target sets .hooks to restrict which hooks it may run on, the bitmask uses NF_INET_ constants. This is only correct for families whose hook layout matches NF_INET_: IPv4, IPv6, INET, and bridge all share the same five hooks (PRE_ROUTING ... POST_ROUTING).
ARP only has three hooks (IN=0, OUT=1, FORWARD=2) with different semantics. Because NF_ARP_OUT == 1 == NF_INET_LOCAL_IN, the .hooks validation silently passes for the wrong reasons, allowing matches to run on ARP chains where the hook assumptions (e.g. state->in being set on input hooks) do not hold. This leads to NULL pointer dereferences; xt_devgroup is one concrete example:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000044: 0000 [#1] SMP KASAN NOPTI KASAN: null-ptr-deref in range [0x0000000000000220-0x0000000000000227] RIP: 0010:devgroup_mt+0xff/0x350 Call Trace: nft_match_eval (net/netfilter/nft_compat.c:407) nft_do_chain (net/netfilter/nf_tables_core.c:285) nft_do_chain_arp (net/netfilter/nft_chain_filter.c:61) nf_hook_slow (net/netfilter/core.c:623) arp_xmit (net/ipv4/arp.c:666) Kernel panic - not syncing: Fatal exception in interrupt
Fix it by restricting arptables to NFPROTO_ARP extensions only. Note that arptables-legacy only supports:
- arpt_CLASSIFY
- arpt_mangle
- arpt_MARK
that provide explicit NFPROTO_ARP match/target declarations.
{
"affected": [],
"aliases": [
"CVE-2026-31424"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-04-13T14:16:12Z",
"severity": null
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: x_tables: restrict xt_check_match/xt_check_target extensions for NFPROTO_ARP\n\nWeiming Shi says:\n\nxt_match and xt_target structs registered with NFPROTO_UNSPEC can be\nloaded by any protocol family through nft_compat. When such a\nmatch/target sets .hooks to restrict which hooks it may run on, the\nbitmask uses NF_INET_* constants. This is only correct for families\nwhose hook layout matches NF_INET_*: IPv4, IPv6, INET, and bridge\nall share the same five hooks (PRE_ROUTING ... POST_ROUTING).\n\nARP only has three hooks (IN=0, OUT=1, FORWARD=2) with different\nsemantics. Because NF_ARP_OUT == 1 == NF_INET_LOCAL_IN, the .hooks\nvalidation silently passes for the wrong reasons, allowing matches to\nrun on ARP chains where the hook assumptions (e.g. state-\u003ein being\nset on input hooks) do not hold. This leads to NULL pointer\ndereferences; xt_devgroup is one concrete example:\n\n Oops: general protection fault, probably for non-canonical address 0xdffffc0000000044: 0000 [#1] SMP KASAN NOPTI\n KASAN: null-ptr-deref in range [0x0000000000000220-0x0000000000000227]\n RIP: 0010:devgroup_mt+0xff/0x350\n Call Trace:\n \u003cTASK\u003e\n nft_match_eval (net/netfilter/nft_compat.c:407)\n nft_do_chain (net/netfilter/nf_tables_core.c:285)\n nft_do_chain_arp (net/netfilter/nft_chain_filter.c:61)\n nf_hook_slow (net/netfilter/core.c:623)\n arp_xmit (net/ipv4/arp.c:666)\n \u003c/TASK\u003e\n Kernel panic - not syncing: Fatal exception in interrupt\n\nFix it by restricting arptables to NFPROTO_ARP extensions only.\nNote that arptables-legacy only supports:\n\n- arpt_CLASSIFY\n- arpt_mangle\n- arpt_MARK\n\nthat provide explicit NFPROTO_ARP match/target declarations.",
"id": "GHSA-9r6p-6xq4-mrq9",
"modified": "2026-04-18T09:30:20Z",
"published": "2026-04-13T15:31:42Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-31424"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/1cd6313c8644bfebbd813a05da9daa21b09dd68c"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3d5d488f11776738deab9da336038add95d342d1"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/3e79374b03bf9a2f282f0eb1d0ac3776f7e0f28a"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/80e3c75f71c3ea1e62fcb032382de13e00a68f8b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/d9a0af9e43416aa50c0595e15fa01365a1c72c49"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/dc3e27dd7d76e21106b8f9bbdc31f5da74a89014"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e7e1b6bcb389c8708003d40613a59ff2496f6b1f"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/f00ac65c90ea475719e08d629e2e26c8b4e6999b"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
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